Sporadic fundic gland polyps: common gastric polyps arising through activating mutations in the beta-catenin gene

Region-specific Wnt signaling responses promote gastric polyp formation in patients with familial adenomatous polyposis

Germline adenomatous polyposis coli (APC) mutation in patients with familial adenomatous polyposis (FAP) promotes gastrointestinal polyposis, including the formation of frequent gastric fundic gland polyps (FGPs). In this study, we investigated how dysregulated Wnt signaling promotes FGPs and why they localize to the corpus region of the stomach. We developed a biobank of FGP and surrounding nonpolyp corpus biopsies and organoids from patients with FAP for comparative studies. Polyp biopsies and polyp-derived organoids exhibited enhanced Wnt target gene expression. Polyp-derived organoids with intrinsically upregulated Wnt signaling showed poor tolerance to further induction, suggesting that high Wnt restricts growth. Targeted genomic sequencing revealed that most gastric polyps did not arise via APC loss of heterozygosity. Studies in genetic mouse models demonstrated that heterozygous Apc loss increased epithelial cell proliferation in the corpus but not the antrum, while homozygous Apc loss was not maintained in the corpus yet induced hyperproliferation in the antrum. Our findings suggest that heterozygous APC mutation in patients with FAP may be sufficient to drive polyp formation in the corpus region while subsequent loss of heterozygosity to further enhance Wnt signaling is not tolerated. This finding contextualizes the abundant yet benign nature of gastric polyps in FAP patient corpus compared with the rare, yet adenomatous polyps in the antrum.

Differential sensitivity to Wnt signaling gradients in human gastric organoids derived from corpus and antrum

Wnt signaling regulates gastric stem cell proliferation and differentiation. Although similar Wnt gradients exist within the corpus and antrum of the human stomach, there are striking differences in gland architecture and disease manifestation that suggest Wnt may differentially regulate progenitor cell function in each compartment. In this study, we tested sensitivities to Wnt activation in human gastric corpus and antral organoids to determine whether progenitor cells have region-specific differences in Wnt responsiveness. Human patient-matched corpus and antral organoids were grown in the presence of varying concentrations of the Wnt pathway activator CHIR99021 to assess regional sensitivity to Wnt signaling on growth and proliferation. Corpus organoids were further studied to understand how high Wnt affected cellular differentiation and progenitor cell function. A lower concentration of CHIR99021 stimulated peak growth in corpus organoids compared with patient-matched antral organoids. Supramaximal Wnt signaling levels in corpus organoids suppressed proliferation, altered morphology, reduced surface cell differentiation, and increased differentiation of deep glandular neck and chief cells. Surprisingly, corpus organoids grown in high CHIR99021 had enhanced organoid forming potential, indicating that progenitor cell function was maintained in these nonproliferative, deep glandular cell-enriched organoids. Passaging high-Wnt quiescent organoids into low Wnt rescued normal growth, morphology, and surface cell differentiation. Our findings suggest that human corpus progenitor cells have a lower threshold for optimal Wnt signaling than antral progenitor cells. We demonstrate that Wnt signaling in the corpus regulates a bimodal axis of differentiation, with high Wnt promoting deep glandular cell differentiation and suppressing proliferation while simultaneously promoting progenitor cell function.NEW & NOTEWORTHY This study demonstrates that human gastric corpus organoids have a lower Wnt signaling threshold to drive optimal growth relative to patient-matched antral organoids. Paradoxically, supramaximal Wnt levels suppress corpus organoid proliferation, yet promote differentiation toward deep glandular cell types while simultaneously enhancing progenitor cell function. These findings provide novel insights into how Wnt signaling differentially regulates homeostasis in the human gastric corpus and antrum and contextualizes patterns of Wnt activation diseases.

Fundic Gland Polyps Lack DNA Content Abnormality Characteristic of Other Adenomatous Precursor Lesions in the Gastrointestinal Tract

Fundic gland polyps (FGPs) develop sporadically (frequently after proton pump inhibitor therapy) or in the setting of a hereditary polyposis syndrome, such as familial adenomatous polyposis (FAP). FAP-related FGPs often demonstrate low-grade dysplasia (LGD) and are frequently associated with APC mutations, even in the absence of dysplasia. Sporadic FGPs with dysplasia are molecularly similar to FAP-related FGPs and demonstrate frequent mutations in APC gene. Despite having similar molecular alterations with colorectal and other adenomatous precursor lesions in the gastrointestinal (GI) tract, FGPs rarely progress to advanced gastric neoplasia (high-grade dysplasia [HGD] or adenocarcinoma), and their role in gastric tumorigenesis remains unclear but likely limited. The clinicopathologic features of 192 patients diagnosed with FGPs, including 86 with FAP-related FGPs (33 with dysplastic FGPs and 53 with nondysplastic FGPs) and 106 with sporadic FGPs (12 with dysplastic FGPs and 94 with nondysplastic FGPs), were analyzed. DNA flow cytometry was performed on 111 FAP-related FGP biopsies, including 32 FGPs with LGD and 79 nondysplastic FGPs, to assess the presence of abnormal DNA content (ie, aneuploidy or elevated 4N fraction). Moreover, 40 sporadic FGP biopsies, including 14 dysplastic (13 LGD and 1 HGD) and 26 nondysplastic FGPs, were examined for DNA content abnormality. Patients with FAP and nondysplastic FGPs were more likely to be younger (mean age, 32 years) and present with multiple FGPs (92%, defined as having ≥2 FGPs) than those with sporadic nondysplastic FGPs (61 years and 65%, respectively; P < .001). They also recorded higher rates of previous or concurrent gastric epithelial dysplasia not occurring in a FGP (8%, P = .016), nongastric GI dysplasia (96%, P < .001), and nongastric GI malignancy (17%, P = .001) compared with those with sporadic nondysplastic FGPs (0%, 52%, and 2%, respectively). The sporadic group was more frequently associated with proton pump inhibitor therapy (78%, P < .001), gastric intestinal metaplasia (24%, P = .004), and a family history of gastric cancer (10%, P = .027) than the FAP group (19%, 6%, and 0%, respectively). Almost all FAP-related FGPs had a polypoid endoscopic appearance (98% vs 84% for sporadic FGPs; P = .009). The mean size of the largest FAP-related FGPs (0.5 cm) was similar to that of sporadic FGPs (0.7 cm) (P = .069). None of the 147 patients with FAP-related or sporadic nondysplastic FGPs were associated with subsequent detection of advanced gastric neoplasia within a mean follow-up time of 54 months (range, <1 to 277 months). However, 2 (4%) of the 45 patients with FAP-related or sporadic dysplastic FGPs developed advanced gastric neoplasia within a mean follow-up time of 59 months (range, <1 to 236 months). One (3%) of the 33 patients with FAP and dysplastic FGPs developed signet ring cell adenocarcinoma, whereas 1 (8%) of the 12 patients with sporadic dysplastic FGPs developed HGD (P = .445). However, none of the FAP-related and sporadic FGP biopsies, regardless of the presence or absence of dysplasia, demonstrated DNA content abnormality. In conclusion, FGPs lack large-scale chromosomal changes that are characteristic of the typical adenoma-carcinoma sequence involved in the development of other GI malignancies. Progression to advanced gastric neoplasia is rare in FGPs, which may be partly explained by the apparent lack of the chromosomal instability phenotype in these lesions.

Incidence and natural history of gastric high-grade dysplasia in patients with familial adenomatous polyposis syndrome

BACKGROUND AND AIMS

Familial adenomatous polyposis (FAP) is characterized by high risks of colonic and extracolonic tumors. Recent studies have suggested a rising risk for gastric cancer (GC). We sought to define the spectrum of premalignant gastric polyps in FAP, focusing on high-grade dysplasia (HGD).

METHODS

The gastric phenotypes of 118 patients diagnosed with FAP or attenuated FAP in our Hereditary Gastrointestinal Cancer Registry were retrospectively reviewed. To analyze the clinical features associated with the diagnosis of HGD, we established an age- and sex-matched control group of FAP patients from our cohort without gastric HGD in a 4:1 ratio.

RESULTS

The spectrum and frequency of gastric polyps in individuals with FAP included fundic gland polyps (67.9%), hyperplastic polyps/foveolar hyperplasia (19.6%), tubular adenomas (15.2%), foveolar adenomas (10.7%), and pyloric gland adenomas (6.3%). Ten patients (8.9%) exhibited gastric HGD at a mean age of 55 ± 13 years, and HGD was seen in all polyp types. When compared with control subjects, HGD was associated with a high diversity of gastric polyp histology, prior low-grade dysplasia, severe gastric polyposis, and prior Whipple surgery (P = 2.0E-5, .003, .024, and .04, respectively). Two patients (1.7%) with HGD were diagnosed with GC. However, the remaining 8 patients with HGD have been under surveillance for an average of 5.8 ± 4.5 years without progression to GC.

CONCLUSIONS

Gastric HGD in FAP may be more common than previously appreciated. The natural history of HGD is variable, and most patients with HGD do not appear to progress to GC.

Transcriptome analysis reveals the essential role of NK2 homeobox 1/thyroid transcription factor 1 (NKX2-1/TTF-1) in gastric adenocarcinoma of fundic-gland type

BACKGROUND

Gastric adenocarcinoma of fundic-gland type (GA-FG) is a gastric malignancy with little relation to Helicobacter pylori. Clinical characteristics of GA-FG have been established, but molecular mechanisms leading to tumorigenesis have not yet been elucidated.

METHODS

We subjected three GA-FG tumors-normal mucosa pairs to microarray analysis. Network analysis was performed for the top 30 up-regulated gene transcripts, followed by immunohistochemical staining to confirm the gene expression analysis results. AGS and NUGC4 cells were transfected with the gene-encoding NK2 homeobox 1/thyroid transcription factor 1 (NKX2-1/TTF-1) to evaluate transcriptional changes in its target genes.

RESULTS

Comprehensive gene expression analysis identified 1410 up-regulated and 1395 down-regulated gene probes with ≥ two-fold difference in expression. Among the top 30 up-regulated genes in GA-FG, we identified transcription factor NKX2-1/TTF-1, a master regulator of lung/thyroid differentiation, together with surfactant protein B (SFTPB), SFTPC, and secretoglobin family 3A member 2(SCGB3A2), which are regulated by NKX2-1/TTF-1. Immunohistochemical analysis of 16 GA-FG specimens demonstrated significantly higher NKX2-1/TTF-1 and SFTPB levels, as compared to that in adjacent normal mucosa (P < 0.05), while SCGB3A2 levels did not differ (P = 0.341). Transduction of NKX2-1/TTF-1 into AGS and NUGC4 cells induced transactivation of SFTPB and SFTPC, indicating that NKX2-1/TTF-1 can function as normally in gastric cells as it can in the lung cells.

CONCLUSIONS

Our first transcriptome analysis of GA-FG indicates significant expression of NKX2-1/TTF1 in GA-FG. Immunohistochemistry and cell biology show ectopic expression and normal transactivation ability of NKX2-1/TTF-1, suggesting that it plays an essential role in GA-FG development.

Long term outcomes of sporadic large fundic gland polyps: a single-center experience

BACKGROUND AND STUDY AIMS

Sporadic fundic gland polyps (FGP) are the most common type of gastric polyp, reported in 0.8%-1.9% of patients undergoing Esophagogastroduodenoscopy (EGD). Data on long-term outcomes of large FGP is limited. We aim to study the natural history of sporadic large (≥ 10 mm) FGPs.

PATIENTS AND METHODS

All adults who underwent EGD for any indication from April 2014 to December 2019 at a tertiary care center were retrospectively assessed, and patients with FGP (≥10mm) were identified. Data on baseline characteristics and long-term outcomes were recorded. Follow-up data were recorded for patients who underwent repeat endoscopy to evaluate for rates of dysplasia and cancer.

RESULTS

A total of 4,000 patients with a diagnosis of FGP were screened and 132 large, biopsy-proven FGPs were included in the final analysis. The most common indication for EGD was gastroesophageal reflux disease (61%). During a follow-up period of 3.2 years, the rate of dysplasia, was 4.0%. Subgroup analysis based on size (10-19 mm and ≥ 20 mm) showed no significant difference in overall outcomes.

CONCLUSION

Repeat EGDs for surveillance should not be routinely performed since large (≥10 mm) sporadic FGPs are mostly benign without significant malignant potential.

Sporadic fundic gland polyps with dysplasia or carcinoma: Clinical and endoscopic characteristics

Fundic gland polyps (FGPs) are the most common gastric polyps and have been regarded as benign lesions with little malignant potential, except in the setting of familial adenomatous polyposis. However, in recent years, the prevalence of FGPs has been increasing along with the widespread and frequent use of proton pump inhibitors (PPIs). To date, several cases of FGPs with dysplasia or carcinoma (FGPD/CAs) have been reported. In this review, we evaluated the clinical and endoscopic characteristics of sporadic FGPD/CAs. Majority of the patients with sporadic FGPD/CAs were middle-aged women receiving PPI therapy and without Helicobacter pylori (H. pylori) infection. Majority of the sporadic FGPD/ CAs occurred in the body of the stomach and were sessile and small with a mean size of 5.4 mm. The sporadic FGPs with carcinoma showed redness, irregular surface structure, depression, or erosion during white light observation and irregular microvessels on the lesion surface during magnifying narrow-band imaging. In addition, sporadic FGPs, even with dysplasia, are likely to progress to cancer slowly. Therefore, frequent endoscopy is not required for patients with sporadic FGPs. However, histopathological evaluation is necessary if endoscopic findings different from ordinary FGPs are observed, regardless of their size. In the future, the prevalence of FGPs is expected to further increase along with the widespread and frequent use of PPIs and decreasing infection rate of H. pylori. Currently, it is unclear whether FGPD/CAs will also increase in the same way as FGPs. However, the trends of these lesions warrant further attention in the future.

Sporadic foveolar-type gastric adenoma with a raspberry-like appearance in Helicobacter pylori-naïve patients

Sporadic foveolar-type gastric adenoma (FGA) has been described as an extremely rare polyp that is whitish and flatly elevated. However, we recently found that sporadic FGA with a raspberry-like appearance (FGA-RA) is not rare in Helicobacter pylori (H. pylori)-naïve gastric mucosa. We endoscopically or surgically treated 647 patients with gastric epithelial neoplasms in the last 5 years, with 7.7% (50/647) being H. pylori-naïve. Among these, 43 FGA-RAs were diagnosed based on histologic and endoscopic features in 34 patients, who were all enrolled in this retrospective study. All lesions were observed by white-light endoscopy (WLE) and narrow-band imaging with magnification endoscopy (NBIME). We subsequently analyzed their endoscopic and microscopic features and patient characteristics. The patients were 22 males and 12 females aged 57±23 years (mean±2SD). WLE showed raspberry-like small polyps mimicking gastric hyperplastic polyps in the oxyntic gastric compartment (body/fundus). Multiple growths were confirmed in 20.6% (7/34) of the patients. NBIME revealed irregularly shaped papillary/gyrus-like microstructures with abnormal capillaries. Histologically, all lesions were intraepithelial neoplasms, and most of lesions (62.8%, 27/43) exhibited low-grade dysplasia. Immunohistochemically, neoplastic cells featured strong and diffuse MUC5AC expression, negative or very low MUC6 expression, and negative MUC2/CD10 expression. They also showed Ki-67 hyperexpression with a mean labeling index of 59.4±48.7%. The coexistence of fundic gland polyps in the background mucosa was significantly higher in multiple FGA-RA cases than in solitary cases (100% vs. 55.5%, P< 0.05). FGA-RA is a newly suggested histologic variant of sporadic FGA whose occurrence is not rare in daily endoscopic practice.

The pathology of gastric and duodenal polyps: current concepts

The liberal use of upper endoscopy has led to an increased detection of gastric and duodenal polyps, which are identified in as many as 6 and 4.6% of patient examinations, respectively. Gastroduodenal polyps are a heterogeneous group of lesions that can be neoplastic or non-neoplastic (e.g. hyperplastic or heterotopical). Most polyps present characteristic topographical features, as well as endoscopic appearance and size. Evaluation of the surrounding mucosa is essential in assessing the underlying pathology (e.g. Helicobacter pylori, autoimmune gastritis or inherited polyposis syndromes). Phylogenetically, gastric and duodenal polyps can be classified according to the epithelial compartment from which they derive. Polyps that arise from the surface epithelium can either be of foveolar or intestinal type, and they can develop from either the native mucosa or the metaplastic epithelium (gastric intestinal metaplasia or duodenal foveolar metaplasia). Other polyps develop from the deeper glandular component, such as pyloric/oxyntic gland derived subtypes. In this review we focus upon epithelial polyps, with an emphasis on the most common and clinically relevant lesions, and present recently described entities.

Recent advances in the pathology of heritable gastric cancer syndromes

Despite the relative rarity of hereditary gastric cancer syndromes, the prompt recognition of their specific clinical features and histopathological characteristics is pivotal in offering patients the most appropriate treatment. In this article, we address the three major inherited syndromes that primarily affect the stomach: hereditary diffuse gastric cancer (HDGC), caused by germline variants in CDH1 and CTNNA1; gastric adenocarcinoma and proximal polyposis of the stomach, caused by germline mutations in promoter 1B of APC; and familial intestinal gastric cancer, which has a poorly defined genetic cause. The main focus will be on HDGC, in light of the recent publication of updated clinical practice guidelines and emerging concepts regarding HDGC histopathology. In particular, we describe the broad morphological spectrum of HDGC lesions, stressing the importance of recognising indolent and aggressive phenotypes. Moreover, we discuss the increased risk of gastric (pre)malignancies developing in patients with other well-defined hereditary cancer syndromes, such as familial adenomatous polyposis, Lynch syndrome, Peutz-Jeghers syndrome, juvenile polyposis, Li-Fraumeni syndrome, and hereditary breast and ovarian cancer syndrome.

Sporadic pyloric gland adenoma associated with a large fundic gland polyp: genetic evidence for stepwise progression

Pyloric gland adenoma (PGA) is an uncommon variant of gastric adenoma exhibiting pyloric gland/mucous neck cell differentiation. We present a sporadic PGA associated with a large fundic gland polyp (FGP) in a woman in her 40 s without Helicobacter pylori infection. The polyp, measuring 25 mm in size, was located in the middle gastric body and was removed by endoscopic submucosal dissection. Histological examination revealed three morphologically distinct components: FGP, FGP with large cysts, and PGA. A genetic analysis identified a truncating APC mutation in all the three components, supporting their histogenetic relationship. Additionally, a GNAS mutation was detected in two components, FGP with large cysts and PGA, whereas a KRAS mutation was exclusively found in the PGA component. Thus, despite the unusual presentation, the PGA component harbored prototypical genetic alterations. The differential genetic alterations observed in the three components imply that they represent stepwise progression from FGP to PGA.

A case of gastric adenocarcinoma considered to originate from a sporadic fundic gland polyp in a Helicobacter pylori-uninfected stomach

We encountered a rare case of gastric adenocarcinoma considered to arise from a sporadic fundic gland polyp (FGP). A woman in her 70 s, who had been prescribed a proton pump inhibitor for 5 years, was referred to our institution for further investigation and treatment of a gastric lesion. White light endoscopy showed numerous isochromatic FGPs in the greater curvature of the gastric body and a 15-mm reddish polypoid lesion with uneven surface characteristics. Magnifying endoscopy with narrow band imaging revealed an irregular granular microsurface structure with irregular microvessels, which is suggestive of cancer. The absence of atrophic changes in the entire gastric mucosa was confirmed endoscopically and histologically, and multiple Helicobacter pylori (HP) tests were negative. An en bloc resection was performed by polypectomy. The specimen showed adenocarcinoma that was thought to arise from an FGP. The lesion consisted of cystically dilated fundic glands in the basal part and neoplastic cells with nuclear atypia and high nuclear-cytoplasmic ratio in the foveolar part; on the basis of these findings, noninvasive adenocarcinoma was diagnosed. Although both adenocarcinoma in an HP-uninfected stomach and epithelial high-grade dysplasia in a sporadic FGP are extremely rare, this possibility should be considered when performing esophagogastroduodenoscopy.

Patients with Gastric Polyps need Colonoscopy Screening at Younger Age: A Large Prospective Cross-Sectional Study in China

Background To date, it is not clarified whether patients with gastric polyps without any alarming symptoms for colorectal neoplasia need colonoscopy screening. The objective of this study is to prospectively determine the association between gastric polyps and colorectal neoplasia.

Methods A multicenter prospective cross-sectional study was performed from July 2012 to December 2014. We compared patients with and without gastric polyps for prevalence of colorectal adenomas. The odds ratios (OR) were computed by logistic regression analysis after multivariable adjustments.

Results Totally 1546 patients were included, with 770 patients in the gastric polyp group and 776 in the age- and sex- matched control group. Patients with gastric polyps had greater odds of having any colorectal adenoma (adjusted OR=2.34, 95% confidence interval [CI]: 1.79 to 3.06, p<0.001) and advanced colorectal adenomas (adjusted OR=2.71, 95% CI: 1.74 to 4.23, p<0.001) than those without. The positive association between gastric polyps and colorectal adenomas remained significant in both women (OR=2.34, 95% CI: 1.66 to 3.29, p<0.001) and men (OR=1.87, 95% CI: 1.31 to 2.66, p=0.001). Patients over the age of 40 with gastric polyps had a higher prevalence of colorectal adenomas than those without (40-49yr: OR=1.81, 95% CI=1.02-3.21, p=0.04; 50-59yr: OR=1.88, 95% CI=1.26-2.81, p<0.001; 60-74yr: OR=2.62, 95% CI=1.73-3.98, p<0.001).

Conclusions The presence of gastric polyps is significantly associated with a higher prevalence of colorectal adenomas, especially advanced colorectal adenomas. Colonoscopy might be considered in patients with gastric polyps, of any gender, and over the age of 40.

Histological analysis of fundic gland polyps secondary to PPI therapy

AIMS

The aim of this study was to clarify the histopathological features of fundic gland polyps (FGPs) in patients treated with proton pump inhibitors (PPIs) and to investigate the mechanism of enlargement of FGPs after PPI treatment.

METHODS AND RESULTS

A total of 196 biopsy specimens of FGPs, which consisted of 87 FGPs in patients treated with PPIs (PPI group) and 109 FGPs in patients treated without PPIs (non-PPI group) were compared histologically using haematoxylin and eosin staining, Ki67 immunohistochemistry and multiplex immunohistochemical stain with Ki67, MUC5AC and MUC6. The significant histological features of FGPs in the PPI group were: larger size of dilated fundic gland cysts, larger number of foveolar and mixture type fundic gland cysts, foveolar cell hyperplasia, parietal cell protrusion, mononuclear cell infiltration and a higher percentage of Ki67-positive cells in the deeper layers of the glands. Multiplex immunohistochemical stain showed that Ki67-positive cells were also positive for MUC5AC, and the Ki67-positive rate was significantly higher in MUC5AC-positive cells of the PPI group than of the non-PPI group. Gene mutations of β-catenin were found in only 9.7% of FGPs in the PPI group.

CONCLUSIONS

Enlargement of fundic gland cysts due to foveolar cell proliferation and parietal cell protrusion might promote the enlargement of FGPs in patients treated with PPIs. β-catenin gene mutations might not be associated with these histological changes of FGPs after PPI treatment.

Gastric foveolar-type adenomas endoscopically showing a raspberry-like appearance in the Helicobacter pylori -uninfected stomach

Background and study aims  Foveolar-type adenoma is described as a very rare tumor that occurs in individuals without Helicobacter pylori (HP) infection and diagnosed as adenocarcinoma in the Japanese Classification of Gastric Carcinoma (JCGC). However, we have frequently encountered patients with foveolar-type adenoma that endoscopically resembles a hyperplastic polyp, suggesting that it has just been overlooked to date. Here, we analyzed clinicopathological characteristics of a special subtype of foveolar-type adenoma showing specific endoscopic findings. Patients and methods  From a total of 212 patients with gastric cancer resected during a 22-month period, we enrolled 14 (6.6 %) diagnosed with foveolar-type adenoma (adenocarcinoma in JCGC). HP infection status was determined by eradication history, HP serum IgG antibody level, urea breath test, and endoscopic and histological findings. All lesions were observed using white-light endoscopy and narrow-band imaging with magnification endoscopy (NBIME). Endoscopically resected lesions were histologically examined. Results  None of 14 patients had a current or past history of HP infection. All lesions were visualized on non-atrophic gastric mucosa as small reddish protrusions with fine granular surface, showing a raspberry-like appearance. NBIME showed papillary or gyrus-like microstructures with irregular capillary. Lesions were histologically diagnosed as foveolar-type adenoma showing MUC5AC-positive gastric mucin phenotype. Ki-67 was overexpressed (median labeling index 69.9 %, range 28.4 - 92.1 %), though all lesions were an intraepithelial tumor without stromal invasion. p53 over-staining was not seen in any. Conclusions  Raspberry-like lesions on non-atrophic gastric mucosa in HP-uninfected individuals should be evaluated for the possibility of a special subtype of foveolar-type adenoma.

Management patterns of gastric polyps in the United States

OBJECTIVE

Recent guidelines on endoscopic sampling recommend complete gastric polyp removal for solitary fundic polyps >10 mm, hyperplastic polyps >5 mm and all adenomatous polyps. We aim to describe endoscopic approach to polyps in the time period prior to the American Society of Gastrointestinal Endoscopy (ASGE) guidelines and to identify opportunities for clinical practice improvements.

DESIGN

Retrospective review of the Clinical Outcome Research Initiative (CORI) database, including all oesophagogastroduodenoscopies (OGDs). Reviewers grouped interventions during procedures based on instruments used for polyp sampling by forceps or snare polypectomy. Logistic regression estimated the effect of variables of interest on method of polypectomy.

RESULTS

Of 783 037 OGDs reported in the CORI database, 25 670 (3.3%) described gastric polyps and met the inclusion criteria. Mean gastric polyp size was 6.5±4.9 mm, and 46.2% and 14.5% were located in the corpus and antrum, respectively. Polyps in the forceps group were smaller than polyps in the snare group (5.7±4.0 mm vs 9.3±6.4 mm, respectively, p<0.001). We identified 1056 polyps (41.3%) >10 mm that only underwent forceps biopsy. Forceps were used more frequently in the gastric fundus.

CONCLUSIONS

Snare polypectomy was underused in gastric polyps, per current ASGE guidelines. Anatomical location and endoscopic features of polyps were important predictors of the approach to gastric polypectomy.

[The Effect of Helicobacter pylori Infection on Recurrence of Gastric Hyperplastic Polyp after Endoscopic Removal]

Background/Aims

Several previous studies suggest that eradication of Helicobacter pylori (H. pylori) leads to the disappearance of gastric hyperplastic polyps. However, little is known about the effect of H. pylori status and eradication on the recurrence of gastric polyps after endoscopic removal. Here, we investigated the recurrence of gastric polyps according to the final H. pylori status in patients who underwent endoscopic removal of gastric hyperplastic polyps.

Methods

Between January 2011 and December 2016, patients who underwent endoscopic removal of gastric hyperplastic polyps and were followed-up for more than two months were enrolled. The success of H. pylori eradication was assessed by histology and rapid urease test or urea breath test, at least 4 weeks after the completion of eradication treatment. At follow-up, the recurrence of gastric polyp was evaluated via esophagogastroduodenoscopy.

Results

Seventy-nine patients were enrolled. During the mean follow-up period of 16.4 months, the recurrence rate of gastric polyp was 25.3%. Among those who received H. pylori eradication therapy, the H. pylori persistent group showed a higher recurrence of polyp than the H. pylori eradicated group; but there was no statistical significance (42.9% vs. 21.7%, p=0.269). Regarding the final H. pylori infection status, the recurrence rate of gastric polyps was significantly higher in the H. pylori positive group than in the H. pylori negative group (42.9% vs. 18.9%, p=0.031). In multivariate analysis, the final H. pylori infection status was a significant risk factor for gastric polyp recurrence after endoscopic removal.

Conclusions

The final positive H. pylori infection status is significantly associated with higher recurrence of gastric hyperplastic polyps after endoscopic removal.

Gastric adenocarcinoma and proximal polyposis of the stomach: diagnosis and clinical perspectives

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) is a recently described, rare gastric polyposis syndrome. It is characterized by extensive involvement of the fundus and body of the stomach with fundic gland polyps sparing the antrum and lesser curvature, an autosomal dominant inheritance pattern with incomplete penetrance, and a significant predisposition for the development of gastric adenocarcinoma. Due to the recent discovery of APC promotor IB mutations (c.-191T>C, c.-192A>G, and c.-195A>C), which reduce binding of the transcription factor Yin Yang 1 (YY1) and transcriptional activity of the promotor, as its underlying genetic perturbation, GAPPS has been added to the growing molecular class of APC-associated disorders. Recent reports on family members afflicted by gastric polyposis due to GAPPS have described the development of metastatic cancer or the presence of invasive gastric adenocarcinoma in total gastrectomy specimens after variable periods of endoscopic surveillance emphasizing the need for an improved understanding of the to-date poorly characterized natural history of the syndrome. There are, however, currently no guidelines on screening, timing of prophylactic gastrectomy, or endoscopic surveillance for GAPPS available. In this review, we summarize the clinical, pathological, and genetic aspects of GAPPS as well as management approaches to this rare cancer predisposition syndrome, highlighting the need for early recognition, a multidisciplinary approach, and the creation of prospective family registries and consensus guidelines in the near future.

Proton-pump inhibitor-induced fundic gland polyps with hematemesis

Fundic gland polyps (FGPs) are generally considered benign. Proton-pump inhibitors (PPIs) are used worldwide as first-line therapy for gastroesophageal reflux disease and nonsteroidal anti-inflammatory drug-induced ulcer treatment. Long-term use of PPIs increases the risk of FGP development. We report an extremely rare case of PPI-induced FGPs with hematemesis. A 37-year-old woman taking daily rabeprazole presented to the hospital with a complaint of hematemesis and tarry stools. Esophagogastroduodenoscopy (EGD) revealed > 20 pedunculated polyps in the gastric body and fundus. Histological examination showed multiple fragments of fundic gland mucosa with dilated glands. Based on these findings and the clinical history, FGPs were diagnosed. Rabeprazole use was discontinued. Repeat EGD performed 9 months later showed a significant decrease in the number and size of the polyps. FGPs are small polyps typically located in the gastric corpus and fundus. They are commonly reported in patients in their 60s and predominantly in females. We conclude that PPI use is a risk factor for the development of FGPs and hematemesis.

Gastric cancer in FAP: a concerning rise in incidence

The highest cancer risks in familial adenomatous polyposis (FAP) include colorectal, duodenal, and thyroid for which surveillance is recommended. Nearly all patients with FAP have gastric fundic gland polyposis (FGP), but gastric cancers are rarely reported with a similar incidence as the general population. We describe a recent, sudden increase in the incidence of gastric cancer in FAP. Seven of the ten cases were diagnosed in the last 20 months. Comparing our population to the SEER database for gastric cancer, the standardized incidence ratio is 140. All cases arose in patients with a carpeting of FGP and associated with large mounds of proximal gastric polyps. Nearly all patients were under upper endoscopic surveillance. This is a concerning observation and reflects a change in the phenotypic presentation of FAP in Western patients.

Sporadic Fundic Gland Polyps and Gastric Acid Suppression Level

BACKGROUND

Fundic gland polyps (FGPs) are a common endoscopic finding and are known to be associated with proton pump inhibitors (PPIs) use. It is not known if their prevalence is affected by gastric acidity levels. This study aimed to assess whether there is a correlation between FGPs and gastric acidity levels as identified on 24-hour ambulatory impedance-pH studies in patients on PPI therapy.

METHODS

We performed a review of 402 consecutive patients who take at least once daily PPI and underwent esophagogastroduodenoscopy with combined impedance-pH studies in the same setting (time and place) between January 2010 and December 2014. Patients were classified into 2 groups based on the presence or absence of biopsy-confirmed FGPs during endoscopy.

RESULTS

Of the 402 patients, 30 (7%) had FGPs. One of these polyps was found with low-grade dysplasia. There was no significant difference of the distributions of the [H⁺] in the FGPs versus the nonpolyp groups (P = 0.741). There was no significant difference between the 2 groups regarding PPI dose frequency regimens (once and twice) (P = 0.074). However, we found weak ordinal association with PPI duration (P = 0.01) (Spearman = 0.1).

CONCLUSIONS

FGPs are common endoscopic lesions. Incidence of dysplasia in FGPs is not only rare, but also of unknown clinical significance. Although they seem to be associated with PPIs, the mechanism remains unclear, as we found no correlation between the presence of FGPs and gastric acid control or PPI dose. Future studies would be useful to elucidate an alternate mechanism.

Fundic Gland Polyps in the Pediatric Population: Clinical and Histopathologic Studies

We retrospectively studied the clinical and histologic features of pediatric fundic gland polyps (FGPs) in 16 patients. FGPs had an endoscopic prevalence of 0.25% in 8527 pediatric gastric biopsies. Five patients had familial adenomatous polyposis (FAP). The median age of onset was 17.7 years in FAP and 17.3 years in sporadic patients. All syndromic patients were asymptomatic and FGPs were identified during surveillance for existing or concurrent colon polyps. They did not take antacids. In comparison, all 11 sporadic FGPs were identified during evaluation of symptomatic patients who had taken antacids (median duration 21 months). Syndromic FGPs can be multiple at single endoscopy and were more likely to recur, while sporadic FGPs were often single. None of the sporadic patients had recurrence of FGPs or a subsequent diagnosis of FAP during a median follow-up of 20.5 months. The dilated fundic glands were lined by parietal and chief cells only in a majority (22/41, 53.7%) of syndromic FGPs, while additional tall mucinous lining cells were found in all sporadic FGPs. Syndromic FGPs did not have parietal cell hypertrophy in the background oxyntic mucosa. Nuclear immunopositivity for beta-catenin was essentially absent in all the FGPs. In conclusion, FGPs were rare in pediatric patients. In syndromic patients, FGPs are asymptomatic and did not precede colon polyps. Prolonged antacid intake seems to be associated with development of sporadic FGPs. Cellular components of dilated fundic glands and background parietal cell hypertrophy can be useful features to eliminate concern for syndromic polyposis.

A Clinicopathologic Evaluation of Incidental Fundic Gland Polyps With Dysplasia: Implications for Clinical Management

OBJECTIVES

Fundic gland polyps (FGPs) can rarely exhibit dysplasia of the surface epithelium. Based on retrospective data, FGPs with dysplasia (FGPDs) are thought to be a strong marker for familial adenomatous polyposis (FAP), although sporadic, non-syndromic FGPDs also occur. Owing to the significant syndromic association, diagnosis of an apparently sporadic FGPD may prompt clinical evaluation for FAP, especially its attenuated variant. We sought to evaluate the positive predictive value of incidental FGPDs for FAP. We also characterized the clinicopathologic features of incidental FGPDs to advance clinical management.

METHODS

Incidental FGPDs were identified from 2004 to 2015 in patients without FAP at biopsy. All clinical follow-up data were reviewed, and germline analysis for APC and MUTYH mutations was performed in consenting patients.

RESULTS

We identified 25 incidental FGPDs in patients not known to have FAP (11.6% of FGPDs, 1.0% of all FGPs). Four patients had a family history of gastric polyps or gastrointestinal cancers. Clinical management included completion polypectomy and gastric endoscopic surveillance (44%), endoscopic surveillance alone (32%), no follow-up (24%), colonoscopy referral (12%), and genetic counseling (4%). Colonoscopies on record revealed 0-7 cumulative adenomas. Follow-up averaged 4.4 years (range 0.3-10.6). No clinical evidence of FAP, gastric cancer, death, or surgery occurred. None of the 11 patients consenting to germline APC and MUTYH testing had genomic alterations.

CONCLUSIONS

Incidental FGPDs in this series were all found to be sporadic (25/25) by endoscopic, clinical, and molecular findings, and thus FGPDs were not harbingers of FAP. As isolated findings, FGPDs do not appear to warrant follow-up genetic counseling or testing.

Correlation between fundic gland polyps and colorectal neoplasms

AIM

To investigate the correlation between fundic gland polyps (FGPs) and colorectal neoplasms.

METHODS

Clinical data of patients who underwent both gastroduodenoscopy and colonoscopy during the period from May 2013 to May 2016 at the First Hospital of Jilin University were retrospectively analyzed. The patients were divided into either an FGPs group (243 cases) or a control group (n = 486). SPSS17.0 software was used for statistical analysis to assess the correlation between FGPs and colorectal neoplasms.

RESULTS

Colorectal neoplasms were detected in 19.8% (48/243) of patients with FGPs, while only in 8.8% (43/486) of the control group. The incidence of colorectal cancer was not significantly different (P = 0.67), while the incidence of colorectal adenoma was significantly different between the two groups (P < 0.001). Stratified analysis showed that the incidence of colorectal neoplasms in the FGPs group was higher than in the control group in females and in patients aged more than 50 years (P < 0.001 for both). Stratified analysis of different parts of colorectal neoplasms suggested that the incidence of colorectal neoplasms in patients who were female or aged over 50 years in the FGPs group was significantly higher than that in the control group, regardless of the proximal colon, distal colon or rectum (P < 0.05).

CONCLUSION

Patients with FGPs, especially females or those aged over 50, have a higher risk for colorectal neoplasms. Colonoscopy is necessary in this group of patients.

Epigenetic regulation of Wnt/β-catenin signal-associated genes in gastric neoplasia of the fundic gland (chief cell-predominant) type

Gastric neoplasia of the fundic gland (chief cell-predominant) type (GNCCP) is a rare variant of gastric tumor. This tumor is associated with activation of the Wnt/β-catenin signaling pathway; however, the mechanisms underlying this activation remain unknown. To elucidate potential roles of Wnt/β-catenin signal-associated gene methylation in GNCCP, we performed β-catenin immunostaining and methylation-specific polymerase chain reaction (PCR) for their associated genes, including SFRPs, APC, AXIN2, and MCC, in 26 GNCCPs [i.e., 11 intramucosal (GNCCP-Ms) and 15 submucosal tumors (GNCCP-SMs)], and compared with 27 fundic gland polyps (FGPs), 12 FGPs with dysplasia (FGP-Ds), 27 conventional gastric adenocarcinomas (CGAs). Nuclear β-catenin labeling indices were higher in GNCCPs and CGAs than in FGPs and FGP-Ds. SFRPs, APC, and AXIN2 were more frequently methylated in GNCCPs and CGAs (SFRP1, 88%/96%; SFRP2, 85%/93%; SFRP4, 73%/81%; APC, 81%/81%; AXIN2, 81%/85%; respectively) than in FGPs and FGP-Ds (37%/50%; 41%/42%; 41%/58%; 37%/33%; 41%/50%; respectively). A significant correlation was seen between nuclear β-catenin expression and methylation of SFRP1 in GNCCPs. Furthermore, nuclear β-catenin expression was significantly frequent in high-methylated GNCCPs than in low-methylated tumors. In conclusion, our results suggest that activation of this pathway, mediated by gene methylation, may be associated with progression of some GNCCP cases, similar to CGAs.

The interaction between the Wnt/β-catenin signaling cascade and PKG activation in cancer

The activation of the Wnt/β-catenin signaling cascade has been well studied and documented in colorectal cancer (CRC). The long-term use of non-steroidal anti-inflammatory drugs (NSAIDs) has been shown to reduce the incidence and risk of death from CRC in numerous epidemiological studies. The NSAID sulindac has also been reported to cause regression of precancerous adenomas in individuals with familial adenomatous polyposis who are at high risk of developing CRC. The mechanism responsible for cancer chemopreventive activity of NSAIDs is not well understood but may be unrelated to their cyclooxygenase inhibitory activity. Emerging evidence suggests that sulindac inhibits the growth of colon tumor cells by suppressing the activity of certain phosphodiesterase isozymes to activate cGMP-dependent protein kinase, PKG, through the elevation of the second messenger cyclic guanosine monophosphote, cGMP. PKG activation has been shown to inhibit the nuclear translocation of β-catenin, reduce β-catenin mRNA and protein levels, and suppress the transcriptional activity of β-catenin. This review describes the relationship between the Wnt/β-catenin signaling cascade and the activation of PKG through PDE inhibition and elevation of intracellular cGMP levels.

Use of Proton Pump Inhibitors and Risks of Fundic Gland Polyps and Gastric Cancer: Systematic Review and Meta-analysis

BACKGROUND & AIMS

There have been increasing numbers of case reports and observational studies of adverse events in patients receiving long-term therapy with proton pump inhibitors (PPIs). The effects of PPI therapy on risks of fundic gland polyps (FGPs) and gastric cancer have received considerable attention. We performed a systematic review with a meta-analysis of randomized controlled trials and observational studies that assessed these risks.

METHODS

We searched the PUBMED, EMBASE, and Cochrane Central Register of Controlled Trials databases for relevant studies published through July 2015. We calculated pooled odds ratio for FGPs and the risk ratio for gastric cancer in PPI users compared with PPI nonusers using fixed- and random-effects models.

RESULTS

We analyzed data from 12 studies, comprising more than 87,324 patients: 1 randomized controlled trial reporting the effect of PPIs on gastric polyps (location not specified), 6 cohort and 1 case-control studies on FGPs, and 1 cohort and 3 case-control studies on gastric cancer. Pooled odds ratios for FGPs were 1.43 (95% confidence interval, 1.24-1.64) and 2.45 (95% confidence interval, 1.24-4.83) from fixed- and random-effects models, respectively. The pooled risk ratio for gastric cancer was 1.43 (95% confidence interval, 1.23-1.66) from each model. We observed significant heterogeneity among studies reporting on FGPs, but not among studies reporting on gastric cancer.

CONCLUSIONS

Based on a systematic review with meta-analysis, long-term use of PPIs (≥12 months) is associated with an increased risk of FGPs. PPI therapy might also increase the risk of gastric cancer, but this association could be biased, because of the limited number of studies and possible confounding factors.

Point Mutations in Exon 1B of APC Reveal Gastric Adenocarcinoma and Proximal Polyposis of the Stomach as a Familial Adenomatous Polyposis Variant

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) is an autosomal-dominant cancer-predisposition syndrome with a significant risk of gastric, but not colorectal, adenocarcinoma. We mapped the gene to 5q22 and found loss of the wild-type allele on 5q in fundic gland polyps from affected individuals. Whole-exome and -genome sequencing failed to find causal mutations but, through Sanger sequencing, we identified point mutations in APC promoter 1B that co-segregated with disease in all six families. The mutations reduced binding of the YY1 transcription factor and impaired activity of the APC promoter 1B in luciferase assays. Analysis of blood and saliva from carriers showed allelic imbalance of APC, suggesting that these mutations lead to decreased allele-specific expression in vivo. Similar mutations in APC promoter 1B occur in rare families with familial adenomatous polyposis (FAP). Promoter 1A is methylated in GAPPS and sporadic FGPs and in normal stomach, which suggests that 1B transcripts are more important than 1A in gastric mucosa. This might explain why all known GAPPS-affected families carry promoter 1B point mutations but only rare FAP-affected families carry similar mutations, the colonic cells usually being protected by the expression of the 1A isoform. Gastric polyposis and cancer have been previously described in some FAP-affected individuals with large deletions around promoter 1B. Our finding that GAPPS is caused by point mutations in the same promoter suggests that families with mutations affecting the promoter 1B are at risk of gastric adenocarcinoma, regardless of whether or not colorectal polyps are present.

Pathology and Genetics of Syndromic Gastric Polyps

Gastric polyps are found in 1% to 4% of patients undergoing gastroscopy. The vast majority are sporadic, but some gastric polyps indicate an underlying syndrome. Gastric polyps can manifest in each of the gastrointestinal polyposis syndromes, including the recently described gastric adenocarcinoma and proximal polyposis of the stomach syndrome. In addition, gastric polyps occur in Lynch syndrome and in a few rare conditions that are not primarily gastrointestinal. While some of these syndromes are clearly associated with an increased risk of gastric cancer, others are not. Interestingly, even in disorders with a well-established risk of gastric cancer, the neoplastic potential and the precursor status of these gastric polyps are not always clear. Although rare, recognition of syndromic gastric polyps is important for individual patient management. These conditions also serve as important models to study gastric homeostasis and gastric tumorigenesis.

Do we need colonoscopy verification in patients with fundic gland polyp?

Background/Aims

The aim of this study was to evaluate the prevalence of colorectal neoplasia in subjects with fundic gland polyps (FGPs) and the relationship between FGPs and colorectal neoplasia in Korea.

Methods

We analyzed 128 consecutive patients with FPGs who underwent colonoscopy between January 2009 and December 2013. For each case, age- (±5 years) and sex-matched controls were identified from among patients with hyperplastic polyps, gastric neoplasms, and healthy controls. Clinical characteristics were reviewed from medical records, colonoscopic findings, pathologic findings, and computed tomography images. The outcome was evaluated by comparison of advanced colonic neoplasia detection rates.

Results

Of the 128 patients, seven (5.1%) had colon cancers and seven (5.1%) had advanced adenomas. A case-control study revealed that the odds of detecting a colorectal cancer was 3.8 times greater in patients with FGPs than in the age- and sex-matched healthy controls (odds ratio [OR], 3.80; 95% confidence interval [CI], 1.09–13.24; P =0.04) and 4.1 times greater in patients with FGPs than in healthy controls over 50 years of age (OR, 4.10; 95% CI, 1.16–14.45; P =0.04). Among patients with FGPs over 50 years old, male sex (OR, 4.83; 95% CI, 1.23–18.94; P =0.02), and age (OR, 9.90; 95% CI, 1.21–81.08; P =0.03) were associated with an increased prevalence of advanced colorectal neoplasms.

Conclusions

The yield of colonoscopy in colorectal cancer patients with FGPs was substantially higher than that in average-risk subjects. Colonoscopy verification is warranted in patients with FGPs, especially in those 50 years of age or older.

Familial Adenomatous Polyposis

Familial adenomatous polyposis (FAP), caused by a germline mutation in the adenomatous polyposis coli (APC) gene on chromosome 5q21, is an autosomal dominant disorder characterized by hundreds to thousands of adenomas throughout the gastrointestinal tract. A variety of extraintestinal manifestations, including thyroid, soft tissue, and brain tumors, may also be present. These patients inevitably develop colorectal carcinoma by the fourth decade of life. In this review, the pathology, epidemiology, and genetic features of FAP are discussed.

Syndromic Gastric Polyps: At the Crossroads of Genetic and Environmental Cancer Predisposition

Gastric polyps occur in 1-4 % of patients undergoing gastroscopy. Although most are sporadic, some gastric polyps are part of an underlying hereditary syndrome. Gastric polyps can be seen in each of the well-known gastrointestinal polyposis syndromes, but also in Lynch syndrome and in several rare not primarily gastrointestinal syndromes. In addition, Gastric Adenocarcinoma and Proximal Polyposis of the Stomach (GAPPS) is a recently described heritable syndrome characterized by isolated gastric polyposis and risk of gastric cancer.Some of these syndromes are associated with an increased risk of gastric cancer, whereas others are not. However, the neoplastic potential and the precursor status of these gastric polyps are not always clear, even in syndromes with a well-established risk of gastric cancer. For instance, the neoplastic potential of Peutz-Jeghers polyps is debatable, despite the well-established risk of gastric cancer in this syndrome. Also fundic gland polyps and gastric foveolar-type adenomas in FAP carry a low risk of malignant transformation. In contrast, gastric juvenile polyps are precursor lesions of gastric cancer in juvenile polyposis syndrome through neoplastic progression of juvenile polyps in these patients.Although these hereditary syndromes with gastric polyps are rare, recognition is important for individual patient management. Furthermore, the initiation and progression of these lesions can be influenced by environmental factors such as Helicobacter Pylori infection. This makes these rare lesions an appropriate model for understanding the clonal evolution of early gastric cancer in the wider population.

Resolution of Fundic Gland Polyposis following Laparoscopic Magnetic Sphincter Augmentation and Subsequent Cessation of Proton Pump Inhibitors

Gastric polyps occur from a variety of sources and are found commonly on upper endoscopy. We present the case of a 49-year-old female who presented for evaluation for antireflux surgery with a history of fundic gland polyposis who required twice-daily proton pump inhibitors (PPIs) for control of her gastric reflux. After verifying that she met criteria for surgery, she underwent an uncomplicated laparoscopic magnetic sphincter augmentation placement. With the cessation of PPIs following surgery, the fundic gland polyposis resolved. Fundic gland polyps may occur sporadically or within certain syndromes, such as familial adenomatous polyposis. Multiple possible inciting factors exist, including the use of PPIs. This is the first reported case of the resolution of numerous fundic gland polyps following the completion of laparoscopic magnetic sphincter augmentation.

Sporadic Fundic Gland Polyps With Low-Grade Dysplasia: A Large Case Series Evaluating Pathologic and Immunohistochemical Findings and Clinical Behavior

OBJECTIVES

Fundic gland polyps (FGPs) occur in two clinical settings, sporadic and syndromic. Epithelial dysplasia is rare in sporadic FGPs, and progression data from large series are lacking. The aim of this study was to evaluate the clinical, morphologic, and immunohistochemical features in a large series of sporadic FGPs with epithelial dysplasia.

METHODS

We studied 85 patients with FGPs with low-grade dysplasia (FGPD), including 62 patients with sporadic and 23 with syndromic FGPDs.

RESULTS

Sixty-two patients with sporadic FGPD comprised 29 men and 33 women with a median age of 56 years. The indications for endoscopy were heartburn and follow-up of Barrett esophagus, and 49 patients had a history of proton pump inhibitor use. Morphologically, sporadic and syndromic FGPDs were similar. Immunohistochemical staining for p53 was normal (weak 1+) in all polyps, Ki-67 immunohistochemistry showed staining in the mucus neck and surface epithelium, and nuclear accumulation of β-catenin was observed in 9 of 40 sporadic FGPDs. Twenty-six (42%) patients with sporadic FGPDs had follow-up esophagogastroduodenoscopies with biopsies after a mean period of 14.8 months (nine with more than one follow-up): nine (35%) had no additional polyps, 13 (50%) had nondysplastic sporadic FGPs, and four (15%) had sporadic FGPDs.

CONCLUSIONS

Sporadic FGPDs were seen primarily in middle-aged patients with gastroesophageal reflux. Follow-up data support the indolent nature of these polyps.

Mutation spectrum in the Wnt/β-catenin signaling pathway in gastric fundic gland-associated neoplasms/polyps

Frequent activation of the Wnt/β-catenin signaling pathway has recently been demonstrated in gastric adenocarcinoma/neoplasia of chief cell predominant type (GA-CCP/GN-CCP) with submucosal involvement. In this study, we examined the activation status of the Wnt/β-catenin signaling pathway in GN-CCP without submucosal involvement, which is referred to as gastric dysplasia-CCP (GD-CCP). We also examined β-catenin expression and the mutation spectrum of PPP2R1A and Wnt pathway genes in 11 cases of GD-CCP, 25 cases of gastric polyps of fundic gland type (GPs-FG), and 21 cases of GPs-FG with dysplasia (GP-FGD). β-catenin nuclear staining was observed in 3 cases of GD-CCP, none of GPs-FG, and 6 cases of GPs-FGD. Mutations in Wnt pathway genes, including PPP2R1A, were observed in 4 cases of GDs-CCP, 10 cases of GPs-FG, and 7 cases of GPs-FGD. Two of these seven GPs-FGD cases showed β-catenin nuclear staining. However, none of the 4 GD-CCP cases with mutations or the 10 GPs-FG cases with mutations showed β-catenin nuclear staining. PPP2R1A mutations were observed in 1 GD-CCP case and 1 GPs-FGD case. Although the mutation spectra of the Wnt pathway genes in GD-CCP and GP-FG differed, based on the absence of β-catenin nuclear staining despite the genetic alterations, GD-CCP is more similar to GP-FG than to GN-CCP, which shows β-catenin nuclear staining and submucosal involvement. Activation of the Wnt/β-catenin signaling by the β-catenin nuclear transition may be required during progression from GD-CCP to GN-CCP. Furthermore, this is the first report describing PPP2R1A mutations in gastric fundic gland-associated neoplasms.

Detection of APC, MYH and AXIN2 gene mutations for screening germline mutations predisposing to familial adenomatous polyposis

AIM: To investigate the significance of detection of APC, MYH and AXIN2 gene mutations in familial adenomatous polyposis (FAP) patients for screening germline mutations predisposing to FAP.

METHODS: Potential APC gene mutations were detected in 5 FAP patients from Yunnan Province, China, by exon-specific DNA sequencing. For samples without already-known APC gene mutations predisposing to FAP, whole-gene sequencing of the MYH and AXIN2 genes was performed.

RESULTS: One novel heterozygous duplication (11198_11200het_delTGT) of the APC gene was observed. One novel heterozygous deletion (11198_11200het_delTGT) was detected in the MYH gene. Four synonymous mutations were found in the AXIN2 gene, of which c.2062C>T(p.L688L) was reported to be a pathogenic mutation.

CONCLUSION: Compared with similar research reports, the positive rate of germline mutation of the APC gene is relatively low in Yunnan Province. To get the full picture of germline mutations predisposing to FAP, MYH and AXIN2 genes should also be tested for FAP pathogenic gene screening.

Signet-ring cell carcinoma arising from a fundic gland polyp in the stomach

Fundic gland polyps (FGPs) are currently the most common type of gastric polyps and are usually benign. However, although rare, gastric adenocarcinoma of FGP has been recently proposed as a new variant of gastric adenocarcinoma. Here we report the first case of a 49-year-old woman with focal signet ring cell carcinoma that arose from an FGP of the stomach. The tumor was completely excised by endoscopic snare polypectomy. FGPs should therefore be evaluated for malignant changes although they occur rarely, if the FGP has an erosive or irregular surface.

GNAS mutation as an alternative mechanism of activation of the Wnt/β-catenin signaling pathway in gastric adenocarcinoma of the fundic gland type

Gastric adenocarcinoma of the fundic gland type (GAFG) is a rare variant of gastric tumor. We have recently reported the frequent accumulation of β-catenin in GAFGs and showed that approximately half of the cases studied harbored at least 1 mutation in CTNNB1/AXINs/APC, leading to the constitutive activation of the Wnt/β-catenin pathway. However, the mechanisms of Wnt signaling activation in the remaining cases are unknown. Accumulating evidence showed that the activating mutation in GNAS promotes tumorigenesis via the activation of the Wnt/β-catenin pathway or the ERK1/2 MAPK pathway. Therefore, we analyzed the mutations in GNAS (exons 8 and 9) and in KRAS (exon 2) in 26 GAFGs. Immunohistochemistry revealed nuclear β-catenin expression in 22 of 26 GAFGs, and 10 (38.5%) of 26 cases harbored at least 1 mutation in CTNNB1/AXINs/APC. Activating mutations in GNAS were found in 5 (19.2%) of 26 GAFGs, all of which harbored R201C mutations. Activating mutations in KRAS were found in 2 (7.7%) of 26 GAFGs, and both of these also contained GNAS activating mutations. Four of 5 cases with GNAS mutation showed nuclear β-catenin expression, and presence of GNAS mutation was associated with β-catenin nuclear expression (P = .01). Furthermore, 3 of these 4 cases did not harbor mutations in CTNNB1, APC, or AXINs, suggesting that mutations in the Wnt component genes and those in GNAS occur almost exclusively. These results suggest that GNAS mutation might occur in a small subset of GAFG as an alternative mechanism of activating the Wnt/β-catenin signaling pathway.